I am designing my first set of skis and was wondering what the advantages of using carbon fiber and kevlar would be over fiberglass? Both materials seem to be included in higher end skis, but do they improve the skis enough (i.e. the kevlar helping to damp vibrations and the carbon fiber creating more stiffness) to be worth the extra investment? Any insights would be greatly appreciated.
Thanks,
Renee
There has been a good discusion here about the virtues of carbon.
http://www.skibuilders.com/phpBB2/viewtopic.php?t=188
And some more info from these sites about both.
http://sweetcomposites.com/Fabric.html
http://www.angstkayak.com/compexp.html
You need to be careful where you place both materials in the composite. Kevlar does poorly in compression, and in a ski needs to be put under the core. It was stated in the above thread that the carbon is poor in compression, but I have found info in my "boatbiulders manual" that carbon rates very high in compression and poorly in tension, so would work best above the core.
IMO, neither is worth the price for a recreational user. Kevlar is 3x the price of glass and carbon is 2x the price of kevlar (in comperable weight). You could make several sets of glass only skies for what you would spend on either of these two materials.
Hafte
Has anyone had any success ordering tri-axial fiberglass from anyone. I ordered a couple yards from snowboardmaterials.com but it's still not here and it has been a month. I ordered some other materials from them also and they also took forever to get here... I have all my other materials I'm just waiting on the glass. I'm excited to get my projects started, so I can try a couple of skis out this winter. Any ideas would be awesome.
Jeff
i recently checked the snowboardmaterials.com site and they put up a note saying that all orders will be delayed until after Christmas or New Years. can't remember the exact details but that's probably what's causing the delay.
maybe someone has some extra that they're willing to sell?
Try some of the boat building guys in Maine. They should be able to give you some scrap, or at least a supplier. Or call vectorply for some samples. Fiberglass supply also has what you are looking for.
Try hamilton Marine in Portland, they will have everything you need. If you make it down here I will fill you in on the progress of my project.
Brian
Brian were you able to get triaxial glass through Hamilton... I called the Portland store and they told me that they don't carry triaxial.
Does everyone else get their triaxial glass through snowboardmaterials.com I've seen vectorply on the site before but, I thought you'd have to order in bulk.
thanks for the ideas...
jeff
http://www.fiberglasssupply.com/Product_Catalog/product_catalog.html
I have been getting some fabrics here. They have always been good to work with. It is a boat building site.
They list lots of biaxial fabrics and only one 22 oz triaxial fabric. I have used a 17 oz. biaxial fabric w/no mat that is two layers of loosely knitted together unidirectional materials.
Is that how the fabrics from snowboard materials are made?
I haven't touched them yet and can't tell from pictures on the site if they are the same.
Hafte
Hi,
Does anyone know what kind of steel usually used for the edge? The only property I could find is that it has to be with a rockwell hardness of 48.
I mean, what series? 1020? 1040? 1060?
and if it is a stainless steel, what are the propeties? how much C, Mn, etc.
And besides the edge, I've read in some places that they put aluminum plates inside the skis. from what aluminum series are the plates?
thanks,
David.
No clue about the edges...
But the aluminum is "Titanal" a brand name. They say the composition is
Al ~88,5%
Cu ~1.7%
Mg ~2.5%
Zn ~7%
Zr ~0.1%
The closest US alloy I found was 7050-T6
Al 89.0
Cu 2.3
Mg 2.3
Zn 6.2
Zr 0.12
It has similar mechanical properties most importantly fatigue resistance, I think...
Thank you!
It is not exactly what I needed but it is also very helpful.
Say, do you know maybe something about the Titanium used in skis?
I think that at least half of what's out there that says "these skis have titanium" is marketing bullshit. Case in point from Karhu:
And unless I'm horribly confused, that's just patently false.
The only skis that I'd believe actually have Ti in them are the Ti Volants [which they don't make anymore] and maybe wierd specialty things like the Salamon AK Rocket Lab. And unless you have a line on cheap Ti it's crazy expensive. Looking at onlinemetals.com [not the cheapest probably] a 3"X4foot strip 0.05" thick would cost ~$85, and that's for "grade 2 Ti." Not that I know what that means exactly, I'd guess it's not the same alloy that's used in things like Ti bikes.
Now if you really want to metal-crazy, trying to see who says they use Ti in their skis I came across LiquidMetal (TM), developed at NASA. It's apparently a zirconium-titanium-nickel-copper-beryllium-pixie dust alloy with strength and elastic properties exceeding Ti or steel. Interesting stuff, it apparently has an amorphus instead of crystalline atomic structure which gives it very little [some of the marketing stuff says "an enery input to return ratio of 1:1" which can't strictly be true] internal friction. I would guess it's impossible to get any, but it looks like Head uses it.
I think metal has pluses as a ski material that composites don't, though I think a lot of people here would disagree. But they're expensive, harder to work with, and you might have the same delamination issues that people have talked about with mixing carbon and glass. But what do I know I'm just some random guy on the internet.
Collin its a common misconception that Titanium is expensive. On the contrary its dirt cheap, even if prices have increased the last year. Still it is one of the least expensive metals around. Here is a quotation from American Metal Market:
"Titanium's ingot, sponge and scrap variations all have increased in price, with sponge-titanium's most refined, purest form-costing the most. According to the American Metal Market, in early 2004, titanium ingot sold for about $5/lb. By mid-2005, ingot was selling for $17/lb. Even scrap increased from about $3/lb. in early 2004 to $10/lb. by mid-2005. Sponge prices jumped even more dramatically".
Titanal only contains 0.2 % Titanium. Its more like a contamination then an ingredient. The name contains it only because of the marketing hype around Titanium.
How did the Austrians think when they combined tit and anal. The porn industry would have been proud of it, but for an alloy.
The thing with Titanium is that its really hard to work with. Processing, casting and so on is awkward. So, the metal is cheap, but when its machined or alloyed it tends to be expensive. Partly because people think of it as a high tech material and partly because its hard to handle.
The easiest way to make skis that look thin, slim and slender and at the same time are fully protected from chipping at the edges, is to use Titanal.
The drawbacks ot the material are that it vibrates as hell. Lots of rubber damping is required.
If you bend it to far it stays bent.
The treatment for bonding, phosphor acid anodized layer only lasts about 6 months.
You get heavy skis.
You have to have two layers of metal, one over and one under the core to balance the camber, otherwise you get peculiar results when temperature fluctuations occur. The metal contracts and expands much more then fibreglass.
Ok, I added up the number's I got from titanal-sports.com and of course I get 99.8%. Leaving 0.2% Ti, my bad.
Why they don't mention it on the list of metals I don't know.
[I may have said this somewhere else allready, but...]
I've been thinking about metals because I've been lusting after the Volkl Mantra's/Explosiv's. Not for any rational reason, since I haven't skied on either.
I'm just not convinced that if you made something as stiff along the ski and torsionally as the Explosiv's using composites it wouldn't end up as heavy or heavier.
When I moved back to Maine I had to get myself a midfat. As luck would have it, I finally got my hands on a pair of 190 Explosiv's (It only took three years to shop form them before annual stock was sold out and I was shorted by 4 cm of cord length.) But what I have been left with is a first class, well tested traditionally designed ski. Obviously these skis are stiff, even though they have a very thin core profile under foot, but mainly acheived by a layer of metal over and under the core.
I put Fritchi FR on them and must say that it is my favorite utility ski in my quiver. Nice width under foot (95mm), straight lines, and best of all an extremely light touring package that will take more abuse than a sitting mule.
